Process of extracting copper from ores.



county of U N lTED I STATES PATENT @FFICE. f

GEORGE D. VAN ARSDALE, OF EAST ORANGE, NEW JERSEY.

PROCES S 0F EXTRACTING COPPER FROM 03.133.

No Drawing. I

To all 1.0710112 it may concern Be it known that I, Gnoncn D. VAN Airs: DALE, a citizen of the United States of America, and a resident of East Orange, Essex, New Jersey, have invented a certain new and useful Improvement. in Processes of Extractin Copper from Ores, of which the following 18 a specification.

This invention relatesto an improved process of changing the copper in ores into soluble copper compounds, dissolving them and then precipitating the copper from the resultant solution, and its object is to provide a simple and inexpensive method of treatment for these purposes.

According to my improved process the ore after it has been ground to desired fineness is roasted with a suitable material to form copper compounds which are soluble m water. ,If copper sulfates are desired, the ore may be roasted, with pyrites if there is not enough sulfur in the ore. Or by roasting it with salt, a product s made from which copper chlorids may be obtamed. These two methods are known as sulfatizing and chloridizing roasts respectively. These methods have not gone into general use for the following reasons: In most cases it has beenimpossible to convert a suflicient amount of the copper by such roasting into water-soluble copper'compounds so that it has been necessary to add an acid at a prohibitive cost. pounds are in solution, the generally proposed method of preeipitatlng 1t bynron has proven to be too expensive and in many cases entirely impracticable because of the difficulty of getting a supply of iron at a reasonable cost. Moreover, iron precipitation produces an impure copper which cannot be marketed directly. Regenerative methods of precipitation have their own difficulties among which is the fact that the solutions become foul from repeated use.

All of the aforesaid objections are obviated in the method I have discovered. This method can be applied in various ways, the details of which may be priced to meet special cases by anyone familiar with copper leaching and precipitation without departing from the spirit of this invention. In the following description of one of the ways of carrying out this invention, it is assumed Specification of Letters Patent.

Then when the copper comthat sulfate solutions are-to be used but where the cost of salt is equal to or as low as that of pyrites, chlorids may be preferred. j When the ore is roasted there should be a suflieient amount of pyrites or other source of sulfur to have at least two parts of suldoes no particular harm. During the ,roasting particular attention should be paid to the temperature and other factors to obtain the llluXllllllll'l amount of copper compounds which are soluble in water. After roasting these compounds are leached out with water which may be acidulated by the addition of a desired amount of liquid from a preceding operatimi, to dissolve the copper present in the form of sulfates and oxids. At the beginning of the leaching operation, it will of course be necessary to use dilute sulfuric acid to acidulate the wash water but after this acid will be generated for this purpose by the process to be hereinafte'r set forth.

The solution is then withdrawn from' the ore as completely as possible and'water or .of this first wash liquid is added to the first liquor or solution to maintain a' desired standard strength and volume of solution for the succeeding steps of the process. The ore which contains the copper which has not been separated by these operations is again subjected to washing with water or weak solution and the resulting second wash 'liquid'passed over iron to recover such cop- 90 per as may be in it and then with its im-. purities allowed to run to waste. By properly choosing the amount of solution r,e-- jected in this way, the main solutions in the cycle of operations may be kept as free from '95 aceuu'iulated impurities as necessary. The first liquor from the ore with the wash solu tion added to it is now subjected to electrolysis in the presence of sulfur dioxid.

The sulfur dionid mav be added to the solu 100 tion either by absorption in a toweryor it may be added to the solution in the electrolytic vats. The latter n'lethod is preferable where. a sulliciently strong gas can be had as it serves to agitate and heat the solu- 105 tions during the electrolysis, both of which Patented Dec. 1, 1914.

Application filed September 20, 1912. Serial No. 721.429.

fur to one of copper. An excess of sulfurare desirable. The amount of sulfur dioxid added may be sufficient to satisfy the equation,-

render this method more economical than any other heretofore proposed.

1 have discovered and described in an application for Patent Serial No. 697,784; filed by me May 16, 1912, that the electrical conditions may be controlled and stopped before the undesirable sulfur compounds of copper begin to be precipitated. In ordinary working the point at which the electrolysis should be stopped is when eighty per cent. of the copper has been precipitated.

arrears After this amount of copper has been thrown down, the remaining solution which contains free acid and the remaining copper is used to dissolve copper from a fresh charge of ore as described.

What I claim is:

A process of extracting copper from its ores comprising roasting the ore with a sulfur compound, leaching out the resulting soluble' copper compound, introducing sul fur dioxid and at the same time separating the copper-from said solution by electrolysis, controlling the electrolysis to cause the deposition of a large portion of the copper in the form of metallic copper, and stopping the electrolysis before sulfid compounds begin to be precipitated.

In witness whereof, I have hereunto set my hand this 15th day of September in the year 1912.

GEORGE D. VAN ARSDALE.

Witnesses J. C. Cnawrono, FRED. W. LIDDELL depict of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

Washington, D. G. 

